Heenan et al. - Brassica hybridisation

New Zealand Journal of Botany abstracts

Experimental hybridisation of Brassica species in New Zealand

P. B. Heenan

M. I. Dawson

R. G. Fitzjohn

Allan Herbarium
Landcare Research
PO Box 40
Lincoln 7640, New Zealand

A. V. Stewart

PGG Wrightson Seeds
PO Box 939
Christchurch 8140, New Zealand

Abstract Field hybridisation experiments are described in which B. juncea, B. napus, and B. oleracea were crossed with B. napus (male), and B. napus was crossed with B. juncea (male). Five of the experiments used chlorsulfuron herbicide-resistant B. napus as the paternal parent, allowing over 98 000 seeds to be easily and efficiently screened for chlorsulfuron resistance to detect hybrid progeny. Two experiments used leaf morphological characters to identify putative hybrids. Intraspecific B. napus crosses produced low percentages (1.83% and 1.79%) of hybrid progeny. Brassica juncea × B. napus interspecific crosses produced on average 2.1% hybrids, and the B. napus × B. juncea cross produced 0.2% hybrids. No hybrids were detected by chlorsulfuron resistance in the B. oleracea × B. napus cross. Fecundity of the F₁ hybrid plants in all of the crosses was low compared with their parents, with hybrids having less than 28% pollen stainability and producing less than 2.4 seeds per flower pollinated when selfed or backcrossed; most of the F₁ hybrids studied produced less than one seed per flower pollinated. These results show that low levels of hybridisation and gene transfer between B. napus and some relatives could occur in New Zealand when grown in close proximity.

Keywords Brassicaceae; Brassica; B. juncea; B. napus; B. oleracea; hybrids; gene flow; chlorsulfuron; New Zealand

B06034; Online publication date 27 February 2007; Received 4 August 2006; accepted 9 November 2006

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